The document discusses the administration of iodine-based contrast media (CM) in CT scans, highlighting the need for weight-based dosing strategies to prevent adverse reactions and ensure effective imaging. It differentiates between total body weight (TBW) and lean body weight (LBW) in calculating appropriate CM doses, noting the significance of individual patient variations. The conclusion emphasizes the potential for using LBW to reduce CM volume and costs while maintaining satisfactory imaging results.

3. Outline
• Introduction
• CM reaction
• Current Practice
• Fix Dose Calculation for all patient
• Base on patientTotal body weight (TBW)
• Lean Body weight (LBW)
• LBW strategies
• Formulas
• Body fatAnalyzer
• Scout Image CT scan
• Sample of Calculation
• Conclusion
• Take home message

4. Introduction
• Contrast media iodine base in CT Scan
• Radiocontrast agents are a type of medical
contrast medium used to improve the
visibility of internal bodily structures in X-ray-
based imaging techniques such as computed
tomography (CT), radiography, and
fluoroscopy. Radiocontrast agents are
typically iodine or barium compounds.When
an agent improves visibility of an area, it is
called "contrast enhancing".

5. CM Reactions
• Mild reactions include:
• nausea and vomiting
• headache
• itching
• flushing
• mild skin rash or hives
• Moderate reactions include:
• severe skin rash or hives
• wheezing
• abnormal heart rhythms
• high or low blood pressure
• shortness of breath or difficulty breathing
• Severe reactions include:
• difficulty breathing
• cardiac arrest
• swelling of the throat or other parts of the
body
• convulsions
• profound low blood pressure

6. • A very small percentage of patients may develop a
delayed reaction with a rash which can occur hours
to days after an imaging exam with an iodine-based
contrast material. Most are mild, but severe rashes
may require medication after discussion with your
physician.
• Contrast-Induced Nephropathy
• Patients with impaired kidney (renal) function should be
given special consideration before receiving iodine-based
contrast materials by vein or artery. Such patients are at
risk for developing contrast-induced nephropathy, in which
the pre-existing kidney damage is worsened.

7. Current contrast media administered at your
department

8. Current Contrast MediaVolume Strategies
Fix Dose Calculation for all patient
Base on patientTotal body weight (TBW)
Lean Body weight (LBW)

9. Fix Dose CM
• The simplest, easiest, and most widely prescribed technique uses a fixed contrast
medium dose and a fixed rate of contrast medium administration.
• This method is reasonably effective in the majority of patients. However, this
technique can result in an over- or under dosage of contrast medium for some
patients.Too little contrast medium may decrease the sensitivity and specificity for
detecting lesions in solid organs, particularly the liver, spleen, and pancreas.
• Too much contrast medium contributes to unnecessary cost expenditure and
increases the risk of renal toxicity, which has been shown to be dose related

10. • All patient, same volume
• Disadvantage
• Fixed iodine dose cause patients with higher BMI tend to have reduced
contrast enhancement.
• Although the magnitude of contrast enhancement is
strongly affected by patient weight, the timing of
enhancement is largely unaffected by this parameter.

11. Total BodyWeight (TBW)
• The most commonly used scheme for adjusting the amount of iodine
mass for the body weight is the use of a 1:1 linear scale (eg, doubling
the iodine mass when the patient’s body weight doubles)
• This method may not provide an accurate adjustment of the required
contrast medium dose for body size, particularly in children and obese
patients
• This is because body fat is less vascular than visceral organs and
muscles and has reduced contributions to dispersing and diluting the
contrast medium in the blood.
• Thus, may cause
• overestimation of the amount of contrast medium needed in obese patients
and vice versa.

12. • Total body weight (TBW).This technique, when
compared with use of a fixed dose, has been
shown to improve the enhancement of solid
organs and vessels, insufficient solid organ and
vascular enhancement still occurs, particularly in
patients with a small body habitus
• Patient-to-patient enhancement variability while
maintaining satisfactory hepatic and vascular
enhancement

13. Graph 1. Simulated contrast
enhancement curves of
the abdominal aorta based on a
hypothetical adult male (30 years old;
height, 170 cm) and varying body
weights (50, 75, 100, and 125 kg) who
underwent injection of 125 mL of
contrast medium (350 mg of iodine
per millilitre) at 4 mL/sec. Magnitudes
of aortic and hepatic contrast
enhancements are inversely
proportional to body weight.

14. Graph 2: Simulated contrast
enhancement curves of the liver
based on a hypothetical adult male
(30 years old; height, 170 cm) and
varying body weights (50, 75, 100,
and 125 kg) who underwent injection
of 125 mL of contrast medium (350
mg of iodine per millilitre) at 4
mL/sec. Magnitudes of aortic and
hepatic contrast enhancements are
inversely proportional to body
weight.

16. Definition
• Lean body mass is a component of body composition, calculated by
subtracting body fat weight from total body weight: total body weight is
lean plus fat. In equations:
• LBM = BW − BF (Lean body mass equals body weight minus body fat)
• Typically lean body mass is 60-90% of the total body mass.
• Men have higher LBM than women.

17. WHAT BODY FAT LEVELS ARE CONSIDERED
NORMAL?
• Essential fat is 2-5% in men, and 10-13% in women.Therefore anything below these levels
is unhealthy.
• To be more gender specific, the recommended amount for women is typically 20-21%,
while the recommended amount for men is 8-14%.
• 15-20% is considered a healthy range for athletes, 21-24% is healthy for fitness, 25-31% is
considered an "acceptable" range and anything above 32% is considered obese.
• The leanest athletes - 5-8% for men, and 10-15% for women.
• Some bodybuilders will often compete at ranges even lower than these levels but will not
sustain these levels off-season, since it is below the essential values and unhealthy to
remain at these levels for any extended period of time.
(Behar, 2016)

18. How to Calculate LBW
•Lean Body weight Formula
•Body fat analyzer
•Estimating LBW

19. Formula
•Lean Body Mass Formula for
Adults
•The Boer Formula:
• Men: eLBM = 0.407weight(kg) +
0.267height(cm) - 19.2
Women: eLBM = 0.252weight(kg) +
0.473height(cm) - 48.3
(Boer, 1984)

20. •The James Formula:
• Men: eLBM = 1.1weight(kg) - 128(weight(kg)/height(cm))2
Women: eLBM = 1.07weight(kg) - 148(weight(kg)/height(cm))2
(Absalom et. Al, 2009)
•The Hume Formula:
• Men: eLBM = 0.32810weight(kg) + 0.33929height(cm) - 29.5336
Women: eLBM = 0.29569weight(kg) + 0.41813height(cm) - 43.2933
(Hume, 1966)

21. •Lean Body Mass Formula for Children
•The Peters Formula:
•This formula fit for children of 13-14 years old
or younger.
• eECV = 0.0215weight(kg)0.6469height(cm)0.7236
eLBM = 3.8eECV (Peters et. al, 2011).

22. Body fat analyzer (Bioelectrical body
composition analyzer scale)

23. Body fat analyzer
(Bioelectrical body composition analyzer scale)
• This is one of the quickest methods.
• Painless.
• This method CAN be accurate (4% margin of error).
• Bioelectrical impedance analysis is available in a laboratory, or for home use
in the form of body fat scales and hand held body fat analyzers.

24. Weakness: Body fat analyzer
(Bioelectrical body composition
analyzer scale)
• Another variable that can effect the amount of body fat this test measures is the amount of
liquid an individual has consumed before the test. As electricity travels more easily through
water, a person who has consumed a large amount of water before the test will measure as
a lower body fat percentage. Less water will increase the percentage of body fat.
• Results are effected by hydration, food intake and skin temperature. If you're dehydrated,
you're body fat percentage will read higher than it is.
• Test can be skewed if taken at different times of the day. For a more accurate result test at
the same time of day, preferably first thing in the morning before breakfast, before
training, and after hydrating.

25. Scout Image; Estimating LBW (eLBW)
TBW x (1-fat_fraction)
• Estimate of patient’s LBW can be obtained from a single transverse CT image, with
the highest level of accuracy obtained from images acquired in the pelvis at the
level of the acetabular roof (Guerrisi, A., et al., 2014).
• The commercially available software three-dimensional (3D) cube tool (VoxTool,
version 6.12.3) was used to calculate the patient fat-fractions for each transverse
CT image.
• This tool applies different attenuation thresholds to a selected image accurately
differentiating fat pixels (attenuation values ranging between -200 HU and -50 HU)
from tissue pixels (attenuation values ranging greater than -50 HU).

26. eLBW
• Figure 3. Antero-posterior scout
view cross-linked (green line) (a)
with the transverse image at the
level of the L5 vertebral body (b),
and automated segmentation of
total body fat of the same
transverse image (c)
• [total fat pixels area/(total fat pixels
area + total tissue pixels area)] ×
100.
• The eLBW equation: patientTBW*
(1-fat_fraction)

27. Sample of Calculation
• Standard protocol involved 125 mL of iopamidol
injected at 4 mL/sec.
• Total body weight (TBW) protocol involved 0.7 g
iodine per kilogram ofTBW.
• LBW protocols involved 0.86 g of iodine per
kilogram (Ho & et. Al,2007)

28. TBW
• Patient 70kg men
• TBW formula = 0.7g/kg
• Contrast media concentration = 370 mg/ml (1.89ml/kg)
•70kg patient x1.89ml/kg = 132.3.6ml

29. LBW
• Formula LBW :TBW x (1 − PBF)
• TBW formula = 0.86g/kg (2.32ml/kg)
• Weight: 70kg
• Percentage Body Fat: 25%
• LBW=70kg x (1-25%)= 52.5kg
•CMVolume (370)= 52.5kg x 2.32ml/kg = 121.8ml

30. Research Based..
•What is the most important in LBW
•Patient-to-patient enhancement variability while
maintaining satisfactory hepatic and vascular
enhancement

31. • Scatterplots show comparison of postcontrast attenuation data between standard (Std), TBW, calculated LBW (cLBW),
and measured LBW (mLBW) protocol groups for (a) liver, (b) portal vein,(c) aorta, and (d) summed measurement.
Superimposed box plots indicate mean (center line) and 1st standard deviation.These scatterplots illustrate that the
average postcontrast attenuation measurements were similar for all protocols

32. Conclusion
•LBW can
• Reduce amount of CM to patient
• Save expenditure on CM
•CM magnitude enhancement among studies is
minimize

34. Take Home Message
•Study
•Research
•Idea

35. References
• Bae, K.T. (2010). Intravenous contrast medium administration and scan timing at CT: considerations and approaches
1. Radiology, 256(1), 32-61.
• Guerrisi, A., Marin, D., Barnhart, H., Ho, L.,Toth,T. L., Catalano, C., & Nelson, R. C. (2014). Optimization of Contrast Material
Dose for Abdominal Multi-Detector Row CT: Predicting Patient Lean Body Weight by Using Preliminary Transverse CT
Images. Advances in ComputedTomography,2014
• Boer P. "Estimated lean body mass as an index for normalization of body fluid volumes in man." Am J Physiol 1984; 247: F632-
5
• Absalom AR, Mani V, DeSmet T,et al. "Pharmacokinetic models for propofol-defining and illuminating the devil in the
detail."Br J Anaesth 2009; 103:26-37
• Hume, R "Prediction of lean body mass from height and weight.". J Clin Pathol. 1966 Jul; 19(4):389-91
• Ho, L. M., Nelson, R. C., & DeLong, D. M. (2007). Determining Contrast Medium Dose and Rate on Basis of Lean Body
Weight: DoesThis Strategy Improve Patient-to-Patient Uniformity of Hepatic Enhancement during Multi–Detector Row CT?
1. Radiology, 243(2), 431-437.
• A. M. Peters, H. L. R. Snelling, D. M. Glass, N. J. Bird "Estimation of lean body mass in children". British Journal of
Anaesthesia1 06(5): 719-23 (2011).